digiKam for 35mm film photographers, Part 1

It may sound strange to some. After all, digiKam is for digital cameras, it says so in its very name. However, nowadays all photographs eventually end up in a digital format, and so I tend to think of photographic film as a form of light sensor with certain, quite favorable qualities. This article, split into two installments, deals with film photography in a digital world, and a tool I wrote to support its use. This first part is about the why. The second part will demonstrate the tool and explain how to use it.

How it all started

A couple of weeks ago I started working on a new tool for the digiKam photo management application. My newly discovered love for shooting 35mm film culminated in buying a Canon EOS-3 SLR and a scanner and I have spent a lot of time trying to get good results from scanning the color negatives directly. It's a problematic process, to say the least.

One of the my reasons for shooting film is how it presents color on the final paper prints, but it's tough to recreate that if you don't scan from prints (it's expensive) but from the developed negative. Getting rid of the orange mask is a trivial challenge, but going from there to a pleasantly looking image on a computer LCD is not. How to develop the films "signature color" without non-reproducible manual intervention?

I started with VueScan which presents itself to be well set for color negative scanning. It got some good, initial results for easy images, but its internal automation is too easily thrown off path. Photos of blue sky? Forget it, the automatic correction creates a muddy gray or mauve but no blue. Also, the amount of film profiles is very limited, for example there are only few Kodak films and none of them are recent. No "New Portra" 160 or 400, no Ektar 100. And yes, you need those profiles to go from a raw, linear scan to something that looks like an photo. Another thing about VueScan is that I don't know what it does and I keep asking myself, is this really how Kodak Gold should look? This ultimately leads to the question of how to recreate the color "signature" of a certain film instead of just getting an "image with nice colors".

Searching for inspiration

When googling for what others do one finds a lot of descriptions of "best settings" for Silverfast or VueScan but nothing that you could devise a script detailing the steps one would need to perform in order to go from Negative to final Image with basic image manipulation tools. Still Google spit out an inspiring article from fellow blogger Obakesan, a Negative-scanning tutorial providing basic input on how to perform most of the necessary steps with the simple level adjustment tool found in any image manipulation software. That article was what eventually culminated in the tool I have written and that just got released together with version 2.6.0 of digiKam, and which I christened, unceremoniously, "Color Negative Inverter", for this is what it does.

The tutorial had a lot of steps to perform manually and didn't fulfill my requirement for reproducibility of images, like hand-adjusting the levels and then manually correcting the colors. You get a photo that looks good as a result but your wife will tell you that her dress had a totally different color that day. Trying to achieve that I went looking for characteristics of film from which I could compute the necessary settings.

How color film works

Chemical film in any format comprises of a plastic carrier film that is coated with light sensitive material. Color negative film for the standard C41 process has three such layers which are sensitive to red, green and blue light and then form a cyan, magenta and yellow color dye. The more light of a specific wavelength hits the film, the higher the density of the resulting color dye. The relation between wavelength, illumination and density is known and published by the film manufacturers in data sheets, like this:

Looking at these one finds that the dye densities for cyan, magenta and yellow map a relatively small density range to a quite large illumination range, and that density range decreases drastically from cyan to magenta to yellow. This mapping has to be translated into parameters for a computer algorithm.

How the Color Negative tool works

First of all, the input data is a linear, raw scan of the film negative, with no corrections like white balance, gamma or tone curve applied. Also, it should be a well exposed scan, using the full dynamic range of the scanner, without clipping of any color channel to null or full scale. Each channel should be represented with 16 bit. The color profile of the scanner output should be known. Your scan program must be able to provide this. I know no free Linux scan program doing that, so I bought VueScan by Hamrick Software. The histogram of such a scan will look like this:

As one can see, the red color channel occupies the widest range while blue has the smallest range. The brightest values of each channel together represent the color of the orange mask. If you adjusted the levels so that the maximum input of each channel matched these values, the orange mask would turn into bright white. This is what the Color Negative tool does to remove the mask.

To map the input range for each channel, one also needs to compute the minimum input. For this task the density profile of the film is used. For Kodak Gold 200, the maximum density just before the shoulder (around the 0.0 point of the exposure axis in the above diagram) is (1.53, 2.00, 2.40) for R, G and B, on a log10 scale. Since we're still talking about a negative image, the maximum density is equal to the minimum brightness. You just need to transform the logarithmic density from the diagram into a linear value. Then apply a gamma correction (globally and to each channel to balance the colors) and you're pretty much there, you just need to invert the image. 

This is as far as the Color Negative tool will take it. From there it's a bit like working with RAW files from a digital camera: You may need to fix the levels and adjust the white balance and tone curve, or use any of the digiKam tools to tweak the photo until it suits your taste.

Collecting film profiles and samples

As best results are achieved with matching profiles for each film, I had to collect data sheets. Not many companies nowadays make C41 film and most of them are by either Fuji or Kodak. I tried finding as many recent and not so recent or even discontinued film data sheets as Google would find. I actually tried verifying the profiles by shooting a roll of each to see how it goes, but some are hard to find today. I think I achieved a good coverage but for some brands like DM Paradies that are re-branded Kodak or Fuji film stock no data sheets exist. For example, some say DM Paradies is Kodak Gold, but looking at the scans I somehow doubt that. If you find data for obscure brands my tool doesn't support yet, I'd be happy to hear about it. Just send me the PDF containing a density diagram like I've shown above. You can additionally send scans to verify the result, just make sure they are linear uncorrected scans with 16 bit per channel. They should also have a bit of the orange mask color around the actual photo. Even better, send me a roll of the film :)

What next?

The basic functionality of the tool is complete, but I would like to add a few features and of course more profiles. One feature will be automatic detection of orange mask values, which is pretty easy to do. For now there is only a color picker so you need to perform a few clicks manually, but fortunately you only need this once for every roll of film, if your scanner has consistent output from picture to picture within a roll. The automatic white point calculation for the negative only requires a bit of searching in the histogram bins and therefore will be easy to do. Suggestions for improving the user interface and also the quality of the conversion? I would certainly like to hear your suggestions.

Stop Racism!

No to SD Demostration
Originally uploaded by Sean Lewthwaite

You may know that the nationalists party in Sweden just managed to enter parliament for the first time. The reaction of the Stockholm people is quick and concise: they're all out on the streets protesting against racism. I found this photo on flickr, my contact Sean was out on the street with his camera and managed to take this fantastic photo! It's marvelous, the way it captures the moment is brilliant. Go and visit his photo stream, there are many more from the "No to SD" demonstration, and say NO to Racism, wherever you can!

ur iphone, ur holdin eet wrong

You know, when the new iPhone 4 was shown to the world, The Steve raved about how the sleek design was achieved by totally making the antennas part of frame. I scratched my head and said to myself, wow, if this works it'll be quite an achievement. Antennas don't like touching. Especially not near the ends where the electric field builds up.

Now, looks like I was too pessimistic about the matter. Of course the antennas do work. You just need to always hold the phone in your right hand. And be cautious where the pinky finger goes. No, NOT right there.

The response of Apple to this matter is just hilarious, as Engadget notes.

Tour Eiffel

Tour Eiffel
Originally uploaded by thinkfat

On Sunday evening Eva and I returned from a long weekend in Paris. We went there with our friends Andrea and Sergio to spend some time in Paris for leisure and to take photos, of course. Sergio and I also went on a night tour with a photo guide, Gilles, who showed us around and gave tips for nice motives in the City of Lights.

I will be posting some photos on my flickr account during the next days.
Enjoy!

Carnival Monday Marathon

P1120749.JPG
Originally uploaded by thinkfat

I like carnival parades! There's no other opportunity to take photos of smiling people, enjoying themselves, in colorful costumes, actually wanting to be seen.

This was my second year joining the crowd in Mayence during the Carnival Monday parade. I love to go there. It is a relaxed and joyful atmosphere and you can get really close to the people, interacting with them. The security is minimal, everybody is just having fun and does not mind a photographer running across the street, diving into the parade, taking images like crazy.

I used only the 45-200 zoom and it did not disappoint. It's fast to focus, light and sharp and the OIS really helps. I filled three memory cards with almost 1000 photos. The set on flickr contains approximately 120 images which I liked most. Many of them are Jpegs right out of the camera, just resized for presentation, some I had to lay hands on, some were developed from RAW.

Come, see and enjoy!

Good Food: Ngoc Lan

In a previous post I ranted against a local "Subways" shop as a prime example for bad food in Darmstadt. I want to share an example for good food today.

Asian restaurants are often laden with kitschy decoration and the menu is mainstreamed to comfort the local taste. Also you have the same dishes with only small variations everywhere. Traditional style cooking is rarely found anywhere.

A very nice example of stylish interior and excellent cooking is the "Ngoc Lan", small Vietnamese restaurant located a bit outside the city centre. You find it at the corner of Bismarkstraße and Steubenplatz, see the map embedded below.


Größere Kartenansicht

We come here once every while and the quality of the food is always great. The cooking is very traditional compared to the standard issue Asia Kim or Dong Dong in more prominent areas of the town. Well cooked, spicy and with fresh herbs, the menu lists many unique meals very different from the usual "fried noodles with chicken/pork/beef". A selection of well mixed, fruity Cocktails can be had as well.

The single room is bright and nicely decorated, calm in minimalist way but not frugal. Go there after dark to experience the full effect of the lighting. There is parking space behind the restaurant, about 15 places in the lot. No need to make a reservation, in fact we never found more than a couple of tables occupied whenever we came there. Which is a pity, because it means it won't stay open for much longer. So go there and enjoy before the place closes for good.

Pockets Picked in Paris

Apart from the obvious Pun, this is what unfortunately happened to me a few days ago. I was buying some snack before entering the train back home at Paris Gare de l'Est and was probably spotted tucking my wallet away. I put it in an outside jacket pocket, a circumstance that immediately retaliated itself as I stood waiting by the platform for my colleagues to arrive.

I was approached by an Asian looking women of middle age and asked for the train to Basel. It struck me odd to be asked for this for my obviously tourist look (after all I was carrying a backpack and a camera bag) but not odd enough to raise my suspicion. While talking to the woman, which took a good amount of time I felt something brush my backpack but again it did not alarm me enough to make me look around. I think I was set up with a classic distraction manoeuvre to give the thief opportunity to pick the wallet from my pocket. It can not have taken him/her more than a couple of seconds despite the pocket being zipped shut.

I did not notice the loss before the conductor asked for my ticket, a good while after the train left the station. I was baffled, but quickly recovered and phoned the emergency hotline of my bank to have the banking and credit cards suspended, avoiding additional financial losses apart from some cash that was in my wallet.

Still, I've now lost my ID, drivers license, credit and banking cards and a couple of other documents that can all be replaced, still there is a significant amount of time and money to be spent now to have them all back. Definitely gives you a sour taste being ripped off like this.

What to learn from this? Crowded places should keep you alert. Strangers approaching you should make you look around for other strangers standing close. Wallets should not be kept in outward pockets. Documents should be kept apart from the money to limit the damage and the amount of time to spend recovering from the loss.

Don't be evil, but a little dense, maybe?

Look what the cat just brought in. Holy cow. Only miscreants and evil-doers fear Google tapping their into their privacy, but the Righteous have nothing to worry about. And it's all the governments fault, anyway.

But this doesn't come as a surprise, does it? Google is an information broker so how can they share anyones concern about information not being another good to sell. However, it's primarily information about people that they collect to drive their advertisement business. This is hardly neutral goods.

I'm wondering if with all this business background Google can still be the best resource when it comes to Internet research. Either the web complexity has grown to a point where they cannot come up with good search results any more or they weigh the results too much towards what their customers think you should be seeing, anyway I found it's becoming increasingly difficult to have good search results with Google. Too many hits are on proxy sites that just pretend to have the keywords you look for and instead reflect to some shady online shops claiming to sell "cold fusion energy cheap"?

So Google has their own DNS now

Google announces their own public DNS now. Some seem to think it's a good move and a fundamental threat to ISPs who are diluting the neutrality of the net. However, I tend to side with the conspirationalists who see it as an attempt of Google to gather even more information about what people do online.

Using the Google DNS you basically allow them insight into any connection your PC performs while it is online. Not about the data exchanged, but at least about what other computers you are connecting to, and not just during web browsing, but also email, instant messaging, chatting, peer-to-peer networking and so forth.

Of course my ISP provides their own DNS and uplink routers are normally configured to use the ISP DNS servers, but I bet Google's Chrome OS will by default use Googles DNS. Guess what I'm not going to use on my private machines.

Now, unfortunately ISPs are known to tamper with DNS queries of their users. If you ever tried to surf a non-existing site you probably found your browser displaying some "navigation aiding" by courtesy of your friendly Internet provider. While meant to be helpful towards their users it bears a threat as well. There you have an infrastructure which is specifically built to intercept connection attempts. While I can't say I actually appreciate this, the way Google harvests data is seriously creeping me out just as much.

Some photos from the summer

I only recently found time to process and upload some photos I took during our summer holiday this year. Instead of going abroad we decided to travel Germany, there are quite a few places we've never been. This year we went East, visiting Thuringia and Saxony. I've uploaded a selection to Flickr, with more to come. Enjoy today some impressions collected visiting Dresden, which marked the end point of our journey.

Control is an illusion?

In a recent interview with the Digital Photography Review web magazine a Nokia representative talks about convergence devices like the N86 mobile phone incorporating an 8MP digital still camera and aiming to replace digital compact cameras in many peoples' pockets. Read the story here.

Seemingly unrelated, The Register has an article about a provider in the United Arab Emirates pushing a trojan horse program as a software update to their customers Blackberry smart phones. The sting was only accidentally discovered and if anything can be learned from that, it is that stuff like that is not just overheated imagination of a few conspiracy theorists but happening right now under our very eyes.

This got me thinking. Do I really want all those features crammed into a connected device I have no control over? Each and every feature requires me to provide more, sensitive information. Phone books are no longer just phone books but store email and postal addresses of my contacts. browsers store web site credentials, Ebay, not to mention PayPal accounts. All my data under the reign of a software that can be changed at any time, without me even noticing.

I may want my camera be a camera, and my mobile phone be just that and nothing else.

Canon vs Tokina 135mm lens shoot out

A couple of days ago I acquired an old Canon A1 SLR camera. Someone was selling off old photo equipment on Ebay and so with the camera came a small collection of four lenses. One of them is a Tokina 135mm f2.8 telephoto. It's quite an impressive item, looking much sturdier mechanically than its Canon FD counterpart. It's made of all aluminium, even the aperture ring is made of metal. It feels quite heavy in your hand and appears to have been well treated since there is no apparent sign of wear. Since I also own the Canon lens, I started wondering which of the two to sell. Casual shooting with both lenses on the G1 didn't reveal major differences in image quality so I did a series of shots under more challenging conditions.

The following photos show performance of both lenses while taking images of a church in my home town against the bright sky before sunset. The sun is hidden behind a cloud layer just outside to the right of the frame on the G1, on a 35mm film camera it would still be inside the frame.

The photos taken with the Tokina are always on the left side. They start at f8 and go up to f2.8, the maximum aperture for both. The lenses feature a built-in hood, it was used while taking the photos but of course for a factor-two crop sensor it's not deep enough. The images were taken as RAW files and then developed without any sharpening or other corrections applied. They were downscaled for presentation and 100% crops of two interesting areas patched on.

Tokina f8

Canon f8

As you can see, at f8 there is not much difference between both lenses. If you look at the 100% crops, there is a slight advantage for the Canon, but it's not obvious. There is a difference in color tone, but I cannot say if its a difference of the lens or just subtle changes in the lighting conditions.

Tokina f5.6

Canon f5.6

At f5.6 the difference is more noticeable. While the Canon lens shows almost no degradation in sharpness and contrast, the photo taken with the Tokina is becoming a little soft with a very slight amount of CA, but it's still pretty good.

Tokina f4

Canon f4

The trend continues at f4, the gap between Tokina and Canon is getting wider. The Canon now starts to show a little softness and a bit of CA, but its overall still pretty good.

Tokina f2.8

Canon f2.8

At f2.8, the Tokina shows a significant loss of contrast and increased softness. Color seams appear around back-lit areas. The Canon has also lost some of the sharpness and contrast it displays at smaller apertures, but its a lot better than its Tokina counterpart.

Summing up, I found the Tokina lens to be performing quite well under most conditions. A challenging environment like strong light sources just outside of the frame requires stopping down to f4 or f5.6 for good image quality. The Canon 135mm however proves to be an excellent lens with good results even wide open.

Digikam hacking

Since a few days I'm officially a contributor to digikam! I even got my old KDE SVN account reactivated and updated and so I can directly contribute code to the project. It started with a bug in the lens correction plug-in I fixed that turned into developing a method to access sub-pixel image data. Currently I'm working on an additional tool for digikam's batch queue manager. This nice feature is particularly helpful for people who need to apply a series of operations to a large number of images at a time.

I'm developing a batch tool to sharpen images, for example after resizing them for print. I found that these two operations, resizing and then sharpening, are a somewhat common constant in my work flow. Usually, I shoot RAW images, import them into digikam directly, then apply white balance, tone curve corrections and sometimes input sharpening. There is little to be automatized there because each image needs different treatment. After this first step I save the post processed images as TIFF. Then, depending on what I do with them, I resize them differently, e.g. 1024x768 for Flickr, 1600x1200 for small prints, etc, and convert to JPEG. Downsampling tends to soften the images, so the final processing step is always a slight sharpen filter.

To demonstrate the effect, take a look at the following two images. The first one was just resized to 1600x1200 pixels, the second one was treated with an Unsharp Mask filter after resizing. It looks more crisp. Click on the images to view them in original size for the full effect.

First holidays with the G1

I remember I didn't write anything about my Easter holidays yet. I went skiing in the Italian Dolomites, to a nice little town in the province of Trento named Moena. Its in the middle of Fassa Valley, a valley in the region of Trentino-Alto Adige where people speak an ancient Rhaeto-Romance language called Ladin. I know this region since I was a kid, we used to go skiing there with all of our family, quite regularly for more than ten years. Moena lies at the foot of the Cantinaccio mountain range, home to the legendary dwarven king Laurin, who was said to having kept a garden of beautiful roses high up near the mountain top. Stories tell he fell in love with a beautiful woman and abducted her. He was defeated by the womans brother and a band of brave knights and taken away into custody, but as a last action he put a ban on his rose garden turning it invisible day and night. But he forgot about dusk, which is not day or night and thus you can sometimes see the mountains glow red of roses in the last rays of daylight when the time is right. So they say.

Easter was late this year but reportedly it had been snowing heavily throughout most of March and April and the conditions were said to be quite good so I took the chance to go there and spend a week skiing and trying my new camera equipment. I had recently bought a Lowe Pro Slingshot 200 back pack that is big enough to hold all my gear, the G1, 14-45, 45-200 and the Canon FD 50 1.4 lens, together with a small tripod and cables, filters, charger, etc. I didn't take the Metz flashgun with me, I have found that it's a part of my equipment I almost never use and since it adds considerable weight I left it at home. I didn't miss it.

I wasn't going there alone. We were a group of around 15 people and we had rented a house for the whole group. A couple of them I knew already from earlier trips to Moena, some of them even from the time I went there together with my parents and brother. The area of Trevalli (Three Valleys) offers quite a number of skiing opportunities. If you have a car, the selection of resorts within 20 minutes travel distance is quite impressive. The image to the left was taken from the top of Col Margherita, which is part of the San Pellegrino skiing resort. Looking at the pictures its hard to believe it was already beginning of April. Not often have I seen this amount of snow that late. However, the warmth of the approaching Spring time was busy melting the snow and even though there was lots of it, its quality degraded massively during the day. So we got up early every day and tried to be on the ski piste soon. That worked rather well, by the time the snow turned soft around 3pm we usually had enough for the day and enough time left to chill, drinking marvelous Italian coffee and eating ice cream.

All the time I carried the Slingshot pack on my back. It was working really well on the piste, I almost didn't feel the weight of the gear and when it was time to enter the lift I could just swing it around from back to front and sit down comfortably. My sun glasses turned out to be a bigger problem, I had to take them off for taking pictures together with my gloves. The viewfinder worked pretty well under the bright sun, I just had to shield it a bit with my hand. The LCD turned out to be mostly useless. I tried to take photos with all the lenses I had, most of them with the 14-45, but some with the 45-200 as well. Sometimes I used a polarizer filter to improve the sky colors and cut down the haze a bit, but still I had to post process most of the images to correct white balance and levels. I used only digikam for raw development and corrections and it handled the task pretty well. I had also taken the MSI U100 netbook with me which allowed me to download the images every evening and inspect them.

I've uploaded a selection of images taken during my stay to Flickr, there's a set named Dolomites. All in all I'm quite satisfied with how the G1 performed. The only thing I'd have wanted is a bit more of dynamic range. One stop more might have made a difference in some situations.

Old Gear, too

Old Gear, too
Originally uploaded by thinkfat

Today a big jumble sale of photo equipment was held at a university facility, it takes place only once a year and it was the first time I went there. It was quite amazing, the mass of gear for sale was huge. Wide selection of stuff from all old and recent camera makers. The selection of Canon FD lenses was not too rich, though.

Still, I was quite successful and got a 28mm f/2.8 for very little money and a 50mm f/3.5 macro lens in very good condition for considerably less than the cheapest ebay offer.

I was tempted to buy a 24mm f/2 and had another good offer for a 24mm f/2.8, but the difference in speed and field of view was too little against the 28mm I already had in my bag and I declined. Instead I took the 50mm f/3.5 macro, I think it will be nice for flower shots and might work as a portrait lens as well.

The 28mm is a particularly nice lens. It's very light and the effective focal length of 56mm is close to a typical film standard prime. I think I'll like it. The 50mm macro is a bit long physically, but also quite light. Not something to have on the camera all the time, but still something to have in your photo bag.

Some first images with both lenses can be found in my flickr photo stream.

Cumulative Weekend Update

Sony Vaio Z21 News:

Some good stuff to talk about since the last weekend update. Lots of activity around Z21 support in the sony-laptop platform module, enough to publish an updated 0.8 release, which Eva has done already through the usual channel. A big update patch was posted on the linux-acpi mailing list, I took parts relevant to the sony-laptop platform module, merged them into our code, fixing some bugs in the way hotkey events were mapped to input events and pushed the fixes back to linux-acpi in order to keep upstream and our version better in sync.

A couple of new features supported now, mostly about wireless kill switch and hotkeys:

• all hotkeys mapped to input events properly
  
• better wireless kill switch support
• compiles on 2.6.27 to 2.6.29
  

On special request I added a new load option to the module, if you insmod sony-laptop.ko with 'speed_stamina=3', the module will not touch the Nvidia graphics card power state any more. This is for people who need the Nvidia card so badly that booting through Windows is the lesser problem.

The Speed/Stamina switch now also reports ACPI events and I've found a way to read the switch position from the embedded controller, that means I can generate distinguishable ACPI events for either switch position.

Regarding enabling Speed mode I have been pointed to the "Nouveau" project which aims to provide a free replacement for proprietary Nvidia drivers. Maybe it's possible to reuse some code from this project to initialize the Nvidia card up to a state where a regular Xorg driver would be able to work with it. That sounds like major additional work, not sure I'll be able to do that on weekend time alone. The learning curve appears to be rather steep. However, since it's likely something that involves userspace code as well, it appears to me the correct way for now is just to report the switch position via ACPI and let userspace code handle the actual switching. Policies should not be hardcoded in kernel drivers anyway.

Digital Photography News:

After trying a Canon FD to µ4/3rds adapter from a Polish ebay seller and finding that it has got a couple of problems with infinity focusing and limits the available aperture stops to f/8, I tried to get a better version from a shop in China. It arrived on Friday a little more than a week after I ordered it and it's in a quite different arena regarding quality.

The Polish one is very simple, cut from just one block of aluminum on a CNC lathe. The adapter from China has a separate bayonet flange screwed to a CNC lathed body and also features an aperture control ring. It works correctly for all F stops and also allows infinity focusing. I'm very happy with it. I also got an almost mint 50mm f/1.4 lense for little money, including even a one year warranty against yet undiscovered defects. Both arrived in time before my easter holidays. I'll be going skiing in Italy, of course taking the camera and all lenses with me and hopefully finding enough time to enjoy both a lot.

Z21 News

Looks like there is some movement on the Z21 front again. Matthew Garret posted a patch to the linux-acpi mailing list with an rfkill based implementation of dealing with wireless devices. Interestingly, his patch also enables all the hotkey events so now I even get an ACPI event when I flip the speed/stamina switch. But still no idea about how to enable speed mode safely.

Eva made a new release with the rfkill changes integrated, which means you can now control all your wireless devices for even more power saving. Grab it from the usual place.

Vintage glass and digital backs

If you're into photography a bit, you probably know the term register distance. It's the distance between the flange of the lens and the sensory plane of the camera body. It's one important factor in lens design and every camera system has its own, a parameter carefully chosen because it has a huge impact on the overall design of all future cameras a maker is creating.

It also defines how easy it is to use lenses of a different system on your own camera. If your camera has a larger register distance than the lens you want to use, it's not doable with just a distance piece, you need some lens in between, which makes it expensive.

Now, the µ4/3rds system, by lack of the mirror box, has about the shortest register distance of any modern digital camera system, which means it's particularly easy to adapt any lens ever made. Just recently a friend, owning a large collection of Canon FD lenses, has bought an adapter to try some pieces of his collection on my camera and by that I got the chance to try some of them myself - and I found it's really a lot of fun.

I'm especially addicted to some of the fast 50mm because they easily offer apertures around f/1.8 and larger, making them very attractive for portrait photography and still motives, the shallow depth of field offering choices in composition impossible with the set of native lenses available for µ4/3rds today. Another interesting choice is long focal length lenses, the photo above was shot using a 500mm reflex lens, quite a compact design and effectively a 1000mm now due to the cameras crop factor.

This experience has considerably changed my plans for future native lenses to buy. Originally I planned to get the 14-140 as a walk-around lens, but it seems it's not going to be as good as the Pana/Leica 14-150 for 4/3rds yet almost as expensive. I'm afraid Panasonic invested too much into making a video lens and sacrificed optical quality, at least the MTF charts suggest that. So, with my newly discovered love for fast primes I'll rather have the 20mm f/1.7 which is supposed to be out late this year.

In the mean time I'll satiate my lust for experiments with vintage glass bought cheap off flea markets or ebay. Having to operate the camera manually is not really a burden and I find the results with the 50mm f/1.4 quite pleasing, and sharper than what I can achieve with the 14-45mm kit lens.

Of course the crop factor has its downsides. It's impossible to find a decent wide angle lens, I tried a Russian made 16mm fish eye and it's not coming out really wide just heavily distorted. I also tried a 24mm f/1.4 "L" for an effective 48mm, and while it works quite well the make is just not fitting the purpose: too bulky, too heavy, all in all not a good fit. I don't want to carry that pound of glass and only use a small fraction of it :-) So that limits the choice to around 50mm, or really long telephoto equipment, I think that's a good variety already.

I hate food abuse!

Recently I became witness to a severe case of food mistreatment. I let my colleagues drag me into one of Darmstadt's fast food "shops", I dare not say "restaurant", Subways. Large international fast food franchise, you'll know them, there's likely one in your town as well. Stood in line, ordered some bread with chicken, salad, sauce. Watched the three stooges behind the counter prepare my meal and swore to never, ever return to that place. The way these people treated the food was unbearable to watch. I have never before seen such disrespect towards edibles, and consequently towards me as the customer buying them.

Of course it didn't taste good. Cold despite valiant efforts with a microwave oven, tasteless, boring, the bread dry like carpet dust and just as disgusting to eat.

Now, maybe the one I visited was just the one bad example, but for me that's the end of the story for good. I'm not opposed to fast food in principle, but there are just too few good ones to make it worth the effort searching. Subways? No Way!

Sony Vaio Z21 News: Switching off Nvidia card seems possible under Linux!

Good news, I think. We've been able to switch off the Nvidia graphics adapter after booting Linux, which means it's possible now to boot directly into Linux and have X11 working with DRI and compositing enabled without the trip through booting into XP first.

It's quite a crude method, though. The hack with acpi_evaluate_object() I mentioned in my previous post worked, I just call the "_DSM" ACPI method of the built in Intel chipset graphics card and instruct it to call the "_OFF" ACPI method of the Nvidia card. I've also found out how to switch the Speed and Stamina LEDs so that you have some visual feedback of what's happening. You cannot see any difference in lcpci, which means that the card is still registered to the bus, apparently it's just powered down. I have no idea currently how to detach it entirely from the bus to reproduce exactly the configuration after having booted XP, maybe through PCI hotplugging? That being said, I have also no idea yet if the card is really powered down entirely.

My wife Eva has uploaded our experimental sony-laptop.c, grab it here. I don't make any guarantees about not damaging your precious toy if you dare trying it.

We're quite pleased with the current status however. It means that Eva can now shut down the laptop without having to make the stupid WinXP detour before using Linux again.

Her detailed log of installing openSUSE 11.1 on the Z21 can be found here.